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Pope’s "catch-all" method and Hensel c d method agree quite well while

Harriot’s method ives relatively high values. The good agreement be-
tween ceiling and wall velocity ratios obtained with Hensel’s method is

C D ncouraging. Hensel's method was used to obtain blockage corrections
for the tunnel tests of the Daytona because o rh this agreement and the

fact that it uses measured velocity data and in this way may account for
differences in vehicle shape. As has been the case with all studies on

blockage corrections for automobiles, these studies how that blockage

corrections are still quite uncertain and should be investigated further.

Figure 2 shows the type of data correlation obtained when the id­

entical model configuration was tested at Wichita State University and

Lockheed-Georgia. Major differences between the tests were ground

plane boundary layer thickness, blockage and bouyancy. The configura­

tion tested was equipped with a large front undernose spoiler which

ignificantly reduced the effect of boundary layer differences by re­

ducing airflow under the model. If it is assumed that the boundary layer

difference was of no consequence, the good correlation obtained is a

measure of the accuracy of the blockage and bouyancy corrections used.

The agreement at larger yaw angles is not as good but is in line with

the assumption on boundary layer effects; i.e.-at large yaw angles the

front spoiler is not as effective in reducing flow under the model and

thus greater differences would be expected.

Good agreement between full-sized tunnel and track data and model

tunnel data was also obtained. Drag and lift coefficients agreed with­

in 5% for most configurations tested, and the use of a large front

C D T) O ler was found to improve agreement as in the tunnel to tunnel com­

parison. In general, the data acquired with the scale models proved to

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